The check engine light is on in my 2000 cherokee. Only one code comes up which is cylinder 1 misfire. I have changed the spark plugs as well as upgraded to neon injectors and had the ecu cleared several times but that didn't help. Could a bad coil cause only one cylinder to misfire? Any other ideas? I need to get this light off asap. Thanks.

O yea. The jeep idles rough and you can feel the skip at an idle but it seems to drive fine once the throttle is pressed. I don't really know if there is a loss of power because I bought it with the cel light.

 

Could be the coil pack.

Also would be a good idea to test compression on all cylinders and see if cylinder #1 is out of spec.

Also know that the 2000 came with the factory 0331 cylinder head, which has a known casting defect between cylinders 3-4. This makes it prone to cracking, especially after an overheat.

The #1 symptom of a cracked 0331 head is LOSS OF COOLANT FROM THE RESERVOIR. So your new hobby is keeping an eagle eye on that reservoir for any unexplained drop in level there.

 

Ok. Its been a while, but I did a compression check and all cylinders are good. The jeep uses no coolant what so ever. I replaced the coil pack with a brand new one from advance. The light is still on for cylinder one, but now I have the code for random multiple misfire. Could I have got a bad coil pack or could it be something else?

 

I'd verify fuel pressure with a gauge. Should have 49 psi, plus or minus 5 psi.

A marginal fuel pressure issue could create the symptoms/codes you are seeing.

Yes it could be something else, but you must rule fuel delivery in or out at this point.